There is a small fee for samples shipped in the continental U.S. This can range from $10-$75. Products shipped outside the continental U.S. can be subject to certain restrictions. Freight charges may range from $75-$300.

Hot Black Oxide

Hot Temperature Black Oxide

EPi's ULTRA-BLAK 400 is simply superior to other hot black oxides.

ULTRA-BLAK 400 is faster, more versatile, and more efficient than any other hot black oxide.

With a superior formula, higher concentration, and no smutty rub off, ULTRA-BLAK 400 will save you a whole lot of time and money.


-High Performance hot black oxide for High Performance Customers-

Benefits of Hot Black High Temperature (285º F - Sodium Hydroxide, Oxidizer Nitrite/Nitrate Bath)

  • 10- 20 minute blackening time: (faster than other hot black oxides)
  • Offers incredible abrasion resistance
  • Lasting corrosion protection: adds years to a part's service life.
  • Beautiful, Glossy blue/black color
  • Fe2O3 is converted into Fe3O4 (magnetite black rust)
  • Meets military spec MIL-DTL- 13924D and AMS 2485 H 

               General Information/ Process notifications

  • Requires ventilation for caustic fumes
  • Boiling solution care required: add water and chemistry
  • Higher capital cost than room temperature process
  • pH adjust waste treatment system

*Will not blacken cast iron or steel castings (turns red/mahogany color.) For cast iron see Ultra-Blak 404


Ultra Blak 400

Black Oxide for Steel is an alkaline salt and oxidizing agent mixture containing penetrants, catalysts, activators, rectifiers and wetters which, when dissolved in water and heated, will produce a black oxide (Fe3O4 - magnetite) finish on steel.

Ultra-Blak 400-L

Black Oxide for Steel is a highly concentrated liquid solution of EPi’s oxidizing salt formulation containing a blend of activators, rectifiers, catalysts, penetrants and wetters

Ultra-Blak OX

A liquid oxidizing agent for blackened steel which does not contain any Sodium Hydroxide. The black oxider purchases 50% by weight liquid Sodium Hydroxide through a local commodity chemical supplier.

Ultra-Blak Rectifier

Liquid Rectifier Additive for Black Oxide Solutions to control excessive build up of iron and copper.